SUMMARY: Project 3 ? The AESOP Study The Iowa Superfund Research Program (ISRP) AESOP Study (Airborne Exposures to Semi-volatile Organic Pollutants) is a community-based participatory research study that assesses inhalation and dietary exposures to PCBs, PCB metabolites, and potential biomarkers among cohorts of adolescent children and their mothers in three Midwest U.S. communities. We previously reported that although intentional production of PCBs as legacy Superfund chemicals ended in the 1970s, production continues as building material byproducts. The AESOP Study identifies the determinants of PCB exposures, including dietary intake and airborne exposure levels indoors and outdoors. In the proposed new funding cycle, the AESOP Study will have an unparalleled opportunity to characterize the role of personal inhalation exposures to PCBs at home and in schools for their contribution to the exposure burden that could result in elevated risks for hormone disruption, metabolic syndrome, and neurobehavioral outcomes. The Specific Aims are: Aim 1: Collect and analyze demographic, residential, occupational, activity, dietary, and health data from AESOP Study participants. Aim 2: Characterize personal exposures to PCB congeners among children and their mothers and apportion exposures to inhalation and diet at the congener level. The study will analyze blood and urine for 209 PCBs and 74 metabolites as well as for biomarkers of thyroid hormone dysfunction, inflammation, and metabolic syndrome. Aim 3: Assess adolescent children?s time-integrated personal exposure to airborne PCBs. Aim 4: Model PCB congener exposures and body burdens; compare modeled and measured data. The study enjoys strong community support garnered through our Community Advisory Boards working with AESOP Study staff and the ISRP Community Engagement Core; this support will help facilitate these aims. The AESOP Study employs bilingual community-based field staff and has enrolled and followed 381 subjects in racially and ethnically diverse communities, providing new insights into airborne exposures and resulting body burdens. The AESOP Study provides human samples and data to other projects within the ISRP, providing enhanced relevance for those projects. De-identified data are widely shared with study participants, the scientific community, and stakeholders at EPA and ATSDR. The AESOP Study has already changed the prevailing views on how most Americans are exposed to PCBs. We have demonstrated that children have substantial exposure to PCB congeners from inhalation at school; their blood shows enrichment with inhaled lower- chlorinated congeners. This has important implications for children?s environmental health that the AESOP Study will further elucidate during the next five years.